Perhaps you should try some spelling variations:
"electrical machine" » "electrical machines", "electric machines", "electric machinery"
"electrical imaging" » "electrical charging", "electrical mapping", "electrical images"
"electrical heating" » "electrical insulating"
"electrical engine" » "electrical engineers", "electrical engineer's", "electrical engineering"
"electrical aging" » "electrical charging", "electrical mapping", "electrical wiring"
"electrical line" » "electrical life", "electrical load", "electrical bio"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("electrical engine") OR ("electrical machine"))) OR ((("electrical line") OR ((("electrical aging") OR ((("electrical imaging") OR ("electrical heating")))))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"electrical engine\") or (\"electrical machine\"))) or (((\"electrical line\") or (((\"electrical aging\") or (((\"electrical imaging\") OR (\"electrical heating\"))))))))".
• Removing quotes may allow a broader search: (((( electrical engine ) or ( electrical machine ))) or ((( electrical line ) or ((( electrical aging ) or ((( electrical imaging ) OR ( electrical heating )))))))).
• Adding a wildcard symbol may retrieve word variants: (((("electrical engine") or ("electrical machine"))) or ((("electrical line") or ((("electrical aging") or ((("electrical imaging") OR ("electrical heating"))))))))*.